I just went for the first ride on my first bike in 15+ years & I am wiped out... from 1.9 miles of riding (in 100+ degree heat at 7pm - gotta love Texas).
I'm 31 years old and have gained about 45lbs in the last 10 years with my wife (weighed in at 225lbs today - 6' 3"). I've tried a few forms of exercise, but get bored too easily & make excuses to quit. About a week ago I started looking at bikes - I ride motorcycles for fun, so the transition to a bicycle seems logical.
I went to the LBS & read a lot here before realizing this was going to cost a bit more than I had imagined. After my realization, I explained to the bike shop that I was planning to buy a used bike on my own & offered to pay for a fitting & a bit of education - they helped me out & explained what (in general) I needed to look for... free of charge. Yesterday I picked up a used bike in great condition, then went back to the bike shop for accessories (helmet, air pump, etc).
I'm in this mostly for fitness, but I expect that I'll enjoy getting out for a ride. My current goal is to be 200lbs by the end of the year, then I'll see where I go from there (I was skin & bones at 180lbs).
How long does it take to build up endurance? 1.9 miles just about killed me! I planned to head out to a freshly paved road with a nice wide shoulder to ride on, but that's 2.5 miles(!!!) from my house.